DE1645533A1 - Process for the preparation of a mixed polymer which is resistant to discoloration and which contains a cyanized vinyl monomer - Google Patents

Description

DR. D. THOMSEN ■ DIPL. ING. H. TIEDTKE DIPL. CHEM. G. ELEMENT

8000 Munich 2 Tal 33 Telephone 0811/226894 Telegram address: Thopatent case K-176 (Tr) / MT'SH 1645533

Munich January 23, 1968

Toyo Rayon Kabushiki Kaishia Tokyo (Japan)

Process for the production of a mixed polymer which is resistant to discoloration and contains an oyanized vinyl monomer

The invention relates to a method of manufacture of a mixed polymer by suspension polymerization in an aqueous medium, which is used as a mixed polymer component contains a cyanized vinyl monomer. -

An interpolymer containing a cyanized vinyl monomer such as acrylonitrile or methacrylonitrile as the interpolymer component contains is, as can be seen, for example a styrene-acrylonitrile copolymer or a styrene-methyl methacrylate-acrylonitrile copolymer which has been found to be a very useful material because of its excellent transparency and processing availability as a thermoplastic resin for compression molding as well as

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visibly different physical and chemical properties is known.

These resins, however, have drawbacks in the tendency to be subjected to thermal treatment as compared with other transparent resins such as thermoplastic acrylic resin and polystyrene to yellow or "dark yellow" at the time of molding.

For this reason, various methods for " preventing discoloration of a copolymer containing a cyanized vinyl monomer such as acrylonitrile have been proposed.

Thus, for example, in Japanese Patent Application Publication No. 7 393/1958 a process, derivatives in which Alkylendiaminallano!, The condensation products of propylene oxide and Alkylehdiamin represent, be a styrene-acrylonitrile Mischpolymermhinzugegeben described, while ^similar in Japanese Patent Application Publication No. 14 936/1960, a process is described in which a volatile organic cyan-developing substance or ammonia is added in the production of an acrylonitrile-containing polymer by block polymerization.

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As a process for the production of a copolymer with containing a cyanized vinyl monomer, there are various polymerization processes, such as block polymerization, Emulsion polymerization, solution polymerization and suspension polymerization and such a copolymer will be by such a polymerization process on an industrial scale Scale made of which the suspension polymerization process the most important polymerisation process because of various Advantages, such as the fact that the manufactured *, "in Resin obtained in spherical or granular shape easily "with others Substances can be mixed and the stage can be easily regulated with regard to the production technology, with opposite all other processes suspension polymerization in aqueous medium is the most important.

! Wenn'man However, the suspension polymerization of a monomeric cyanisierten Viny, for example acrylonitrile executes in an aqueous medium \ can due to the substantial solution of the cy'äh '"isie; rten Vinylmoriomeren in v / ater aisser desired da * I <Ionoir.erenmischung and The spheres with the desired particle size result in ion-polymerized particles which are colored as a result of the heating at the time of molding or lead to a clouding of the molded article and, in an extreme case, they can even be a cause of deterioration.

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yellow the bead slurry within the polymerization stage will.

To overcome these difficulties, the above-mentioned known methods could not prevent the discoloration sufficiently effectively and accordingly the fact remains that there has been no method for the direct production of a copolymer containing a cyanized vinyl polymer by suspension polymerization in aqueous media has given that has sufficient resistance to discoloration. ,. ■ ■

The object of the invention is to create a method for the preparation of a mixed polymer which is resistant to discoloration and which contains a cyanized vinyl monomer by suspension polymerization in an aqueous medium.

In the effort to solve the problem, it was found that it is carried out by carrying out the suspension polymerization in an aqueous medium after adding a higher saturated aliphatic Alcohol to a cyanized vinyl monomer to be polymerized is possible, the recovery of emulsion-polymerized Particles noticeably degrade and the discoloration of the beads thus obtained from the polymer as a result of heating was remarkably decreased at the time of compression molding. '

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The term “a cyanized vinyl monomer” used here is a compound of the formula

CH ₂ = C _n

CM,

in which R is hydrogen or a lower alkyl group - and im Case of a lower alkyl group - preferably in particular CH. ^

The invention includes a method in which a suspension polymerization of a vinyl copolymer is carried out in an aqueous medium, which is at most 4o percent by weight of at least one of the cyanized vinyl monomers of the formula mentioned contains, ol to 5 parts by weight a higher saturated aliphatic alcohol of the formula

^C n ^H 2n ₊ -l ^0H >. ■ - ■ ..; ... · ·

in which η is an integer from 12 to 18, to 100 parts by weight of the monomers mentioned are added, whereby an opposite Discoloration resistant mixed polymer with a content of a cyanized vinyl monomer.

In the method of the invention, the remaining mix is 009818/1839

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monomers (at least βο percent by weight) associated with the cyani ~ is copolymerized, at least 1 vinyl mixed monomer which is copolymerizable with the cyanized vinyl monomer is selected from the group of an aromatic vinyl monomer of the formula

in which both R and R ^{f are} hydrogen or a lower alkyl group and an acrylic monomer of the formula

CH ₂ = C - CO.OR ₂

in which R ^ is hydrogen or a lower alkyl group and Rp mean a lower alkyl group.

In the mixed monomer there is an aromatic vinyl monomer in particular styrene and, as an acrylic monomer, in particular methyl methacrylate preferred.

Furthermore, in the suspension polymerization in 'aqueous Medium according to the invention, the polymerization reaction mixture below Io weight percent of a plasticizer or a

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rubber or according to schuitähnli ehe polymeric substance (e.g. polymers from butadiene, such as butadiene homopolymer, a butadiene-styrene-Mi chpolymereSj a butadiene-acrylonitrile mixed polymer or isoprene polymers such as polyisoprene or natural Rubber and the like.) Contain. The reaction mixture can also be a commonly used light stabilizer or Heat stabilizer contained in a small amount. * ■

The discoloration of a cyanized vinyl monomer containing Mixed polymers does not occur too strongly »if the Content of eyanized vinyl monomers below lo However, the discoloration becomes noticeable when the content is at least 10% by weight.

In the method of preventing discoloration according to the invention, it is important to add saturated aliphatic alcohols having 12 to 15 carbon atoms to the aqueous suspension polymerization system. An alcohol having not more than 11 carbon atoms, the volatility of the obtained polymers in the time is not preferable because its boiling point is low, '' point of compression molding is strong and foams in the resulting formed article produced earthed v /, while an alcohol having at least 19 Carbon atoms are practically difficult to obtain and economically disadvantageous. A saturated one

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Aliphatic alcohol having I ¹ J to 18 carbon atoms is particularly preferred because, when such an alcohol is added, any silver streaks or stain marks are hardly formed in molding resins and the thermal deformation temperature and softening point are hardly lowered.

The amount of these alcohols added, based on 100 parts by weight of the monomer used is from 0.2 to 1 part by weight, preferably from 0.2 to 1 part by weight; at a lower one The amount added, the discoloration-preventing effect is considerably reduced, while with a larger amount added the prevention of discoloration is obtained, but the transparency of the resin deteriorates and also the mechanical Properties of the resin are reduced.

The suspension polymerization in an aqueous medium according to the invention is practiced in a manner known per se .

The polymerization initiation reaction is normally Triggered by a free radical forming agent, however, it can can also be triggered by fawns.

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A peroxide (hydroperoxide-containing) or an azo compound can be used as such a free radical generating agent can be used, but in general an azo compound is preferred over a peroxide. The effect namely, the present invention is particularly remarkable when an azo compound is used. As a preferred Azo compound can be azobisisobutyronitrile and azobisdimethylvaleronitrile to be named.

A suspension stabilizer in suspension polymerization in aqueous medium, an inorganic colloidal substance such as barium sulfate and calcium carbonate, or a water-soluble organic high molecular substance such as polyvinyl alcohol, carboxymethyl cellulose and sodium polymethacrylate can also be used.

In general, the concentration to be used will be of these suspension stabilizers in the range of 0.5 to 3 parts per 100 parts of the monomer in the case of an inorganic one Suspending agent and in the range from .o, oo5 to. 0.05 parts per 100 parts of the monomer in the case of a water-soluble one high polymer substance. .

The concentrations of the monomers in the execution

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• suspension polymerization in aqueous. Medium generally 1/2 to 1/3 of the monomer to the water content. The reaction temperature is at the time of Polymerization 50 to 14o ° C and the pH value is in the range from 4 to Io. .

The invention is illustrated by the following examples explained in more detail, in which parts mean parts by weight.

Example 1

In a mixture consisting of 75 parts of styrene and 25 parts Acrylonitrile, 0.4 parts of azobisisobutyronitrile and 0.2

Parts of n-dodecyl mercaptan, 0.5 parts of cetyl alcohol of the formula Ο ^ Η ,, ΟΗ were dissolved and mixed, the mixture was added dropwise to 250 parts of an ion exchange water in which 1.0 part of BaSO ₁ , as _a suspension stabilizer, is colloidally dispersed and the resulting aqueous solution was suspended with stirring, the temperature was increased from 70 ° to 120 ° C within 5 hours and the .aqueous solution was polymerized in ^ gas. The polymer beads obtained after slurrying the polymer were dehydrated, washed with water and dried, and then a 1 mm thick sheet was formed by press molding.

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For comparison purposes, a sheet material was used prepared from a mixture of monomers containing no ceryl alcohol by exactly the same procedure. the Transparency of these two sheet-like materials was measured at a wavelength of 150 μm and the measured values were taken as an indication of the discoloration. The following results were obtained. ·

. Kischpolyiseres made of styrene / acrylonitrile (75/25)

Cetyl alcohol. Light transmission

(a) Addition of 0.5 part 89.1 & ^:

(b) no addition £ 75.3.

After. the two materials to 18o ° to 19o ° C in Air heated for 20 minutes became similar Measurements carried out.

Cetyl alcohol light transmission. (^ 5ο mu %)

(a) Addition of 0.5 parts

(b) no addition

len 2 88 , 3 « 51 3example

In a mixture consisting of 7o parts styrene, 3o parts 009818/1839

len acrylonitrile, ο.8 parts of lauroyl peroxide and 0.4 parts of n-dodecyl mercaptan vmrde l, o part of lauryl alcohol of the formula ^c ₁ 2 ^H 25 ^0I ' ⁱ S ^elo ' ^{st and} mixed; the resulting mixture was suspension polymerized in 200 parts of ion exchange water at 80 to 100 ° C. using polyvinyl alcohol as the suspension stabilizer. The obtained polymer beads were dehydrated, washed with water and dried, and in the same manner as in Example 1, a sheet 1 mm thick was prepared.

As a comparative example, a web of a reaction system, that did not contain lauryl alcohol V / also manufactured. The light transmission of these two tracks was measured at a wavelength of 45o .mu.m.

Mixed polymer ais styrene / acrylonitrile (70/30)

Lauryl alcohol light transmission (45o mu %)

(ä) Addition: l, o part example 3 88 , 2% . "(D) no encore

Into a mixture consisting of 70 parts of styrene and 30 parts 009818/1839.

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Acrylonitrile, ο.8 parts lauroyl peroxide and ο.4 parts n-dodecyl mercaptan l, o myristic alcohol of the formula C ^ ELqOH was dissolved and mixed; the resulting mixture was dissolved in 200 parts of ion-exchanged water at 80 ° to 100 ° C using suspension polymerized by polyvinyl alcohol as a suspension stabilizer. The obtained granular polymer was dehydrated, washed with water and dried, and therefrom a 1 mm thick sheet produced as in Example 1.

As a comparative example, a sheet from a reaction system containing no myristic alcohol was passed through a corresponding working method produced.

The light transmission of these two webs was at a wavelength of 45o mu. measured.

Mixed polymer made of 'styrene / acrylonitrile (7o / 3o)

Myristinal cabbage light transmission (45o mu .%)

(a) Addition: l, o part 8752

(b) no addition

Example 4

In a mixture consisting of 70 parts of styrene, 3o parts

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len acrylonitrile, o, 15 parts of azobisisobutyronitrile, o, 3 parts of 2,2'-azobis-C2, Ji-dimethylvaleronitrile) and o, H parts of n-dodecyl mercaptan, l, o part of lauryl alcohol of the formula CH OH was dissolved and mixed and using • poly vinyl alcohol as a suspension stabilizer, the resultant mixture in 2oo parts of ion exchange water was first So at ⁰ C for 3 hours and then 'at loo ° C - aBpensionspolymerisiert - tei Steigerung- the temperature of 6o ° C for 1 hour. The obtained spherical polymer was dehydrated, washed with water and dried, and in the same manner as in Example 1, a sheet 1 mm thick was prepared therefrom.

, As a comparison example, a system that does not have a Containing lauryl alcohol, a sheet was made by the appropriate procedure.

The transmittance of these two sheets was measured at a wavelength of 45o wji.

Mixed polymer made of styrene / acrylonitrile (7o / 3o}

Lauryl alcohol

Light transmission (45o τημ%)

(a) Addition: 1, ο part

(b) no addition

86% 69%

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Example 5
Example 1 was repeated with the exception that a

Mixture of o _f 25 parts of stearyl alcohol with 0.25 parts of cetyl alcohol was used as the higher saturated aliphatic alcohol, a mixed polymer of styrene / acrylonitrile (75/25) being obtained once with the addition of the higher alcohol and once without this addition » '

The results of the light transmission measurement of
1 mm thick strips of the copolymers obtained at a wavelength of 45ο ιψ. and 650 mu were as follows.

Mixed polymers made of styrene / acrylonitrile (75/25)

Mixture ujit translucent - translucent higher ality (45ο <τψ.) - (65ο τψ)

alcohol

(a) addition; ο, 3 parts 89.0 ^ 89.6 ^

(b) no addition. 74.2 % 82.35S

Example 6

Example 1 Λ -rde repeated with the exception that JTeth-

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acrylonitrile used instead of the acrylonitrile used there became. The light transmittance of the webs obtained in this way was measured. As shown in the table below too can be seen, the results show that the addition of cetyl alcohol provides excellent thermal stabilization Discoloration has been achieved.

Mixed polymer. Styrene / acrylonitrile = (75/25)

Ceryl alcohol light transmission ( ¹ ISo mu. %)

(a) Addition: 6.5 parts 87, ο #

(b) no addition $ 72.1

Example 7.

"A monomer mixture" consisting of 50 parts of styrene,

40 parts of methyl methacrylate, 10 parts of acrylonitrile, Oj2 parts n-dodecyl mercaptan and 0.4 parts of azobisisobutyronitrile, ' to which 0.3 part or “no cetyl alcohol was added,” was suspension polymerized as in Example 2. It was the Light transmission of the spherical polymers obtained at a wavelength of 45o np v / ie in Examples 1 to 4 measured. -The following results were obtained.

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Mixed polymers made from styrene / Kethylmethacrylat / Aery1-nitril C5o / Wla)

Cety! Alcohol light transmission (45o mji

(a) Addition: ο, 3 parts 9o _f 6%

(b) no addition 85.3 #

Example 8

In a mixture consisting of 75 parts of styrene, 2o parts of acrylonitrile, 5 parts of methacrylonitrile, o.4 parts of azohisisobutyronitrile and 0.2 parts of n-dodecyl mercaptan, 0.5 parts of cetyl alcohol of the formula C ^ gH ,, OH dissolved and mixed. The mixture was under. _v use dropwise of l, o parts BaSO ₁ ,, which was colloidally dispersed as a suspension stabilizer in 25o parts by ion exchange water, and the decision "standing mixture was stirred and suspended, was and increases as the temperature of 7 ° ° to 12o ° C , it was polymerized in K ₂ gas atmosphere. the Folymerkügelchen obtained after the slurry was dehydrated, washed NIIT water, dried and then a 1 mm thick. sheet was prepared by press molding.

For the Vergleicbtzwecke no GTety was from the monomer ,,! Alcohol _s contained by the corresponding labor

wisely made a path. '

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It became the light transmission of these two webs measured at a wavelength of 45o nju. The results were assumed to be signs of discoloration and were as follows.'

Interpolymer of styrene / Acrylnnitrii / methacrylic • nitrile (75/2 _0/5)

Cety! Alcohol

Light transmission (k5o mu %)

(a) Addition: p, 5 parts Cb) no addition

8.8 "

in the

-After heat-treating the two webs in air for 20 minutes the same measurements were carried out, the following results were obtained.

Cetyl alcohol

Light transmission C45o mp %)

Ca) Encore • : 0.5 Parts = ~ 87 Cb) no Encore 9 "-52 example *

In a mixture consisting of Jo parts of styrene and "25 parts of acrylonitrile, 5 parts of polybutadiene dissolved no gels contained. To the resulting solution were ό,

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Parts of azrobisisobutyronitrile were added. This composition was polymerized at 70 ° C. for 1 hour, to the resulting prepolymer, 0.2 parts of n-dodecyl mercaptan and 0.8 part of lauroyl peroxide were added and dissolved therein; the resulting solution was added dropwise to 200
Parts of ion-exchange water, ₁ J. .waren colloidally dissolved as a suspension agent in the 1.5 parts of BaSO, was added, the temperature was raised ⁰ C within 4 hours "by 7o ° C to Ho and the entire aqueous solution was in N ₂ -GaS atmosphere polymerized. The spherical polymer obtained was dehydrated, washed with "water and dried. Further, polymerization was carried out by exactly the same procedure from the rubber cement to which 0.5 part of cetyl alcohol was added to obtain spherical polymer. From these two kinds of beads, 2 sheets as in Examples 1 to 5 were prepared. which were heated in air at 180 to 19o ° C for 20 minutes and the respective degree of discoloration was assessed with the naked eye.

Mixed polymer made from styrene / acrylonitrile / polybutadiene

(7O / 25/5) Degree of discoloration Cetyl alcohol yellow
Brown Addition: ο, 5 parts
no encore

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From the examples above is the effect of the procedure apparent after the invention.

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Claims (8)

-Xh. ■■■ ** '"Patent claims. .. · ..: 1) Method of making an opposite discoloration stable mixed polymers with a content of a cyanized Vinyl monomers, in which a vinyl copolymer polymerizes by suspension polymerization in an aqueous medium is that less than 4o percent by weight of at least one cyanized vinyl monomers of the formula. , = C S - CN, in which R is hydrogen or a lower alkyl group, · preferably CH, is, contains in copolymerized form, characterized in that that one o, ol to 5 parts by weight of at least one higher saturated aliphatic alcohol of the formula in which η is an integer from 12 to 18, too loo by weight. .Share all of the monomers. 2) Method according to claim 1, characterized in that that acrylonitrile is used as the cyanized vinyl monomer. O ₀₉₈₁ 8/1839 -Zl- 3) method according to one of the preceding claims, characterized in that the higher saturated aliphatic alcohol is added in an amount of from 0.2 to 1 part by weight to 100 parts by weight of the total monomers. 4) Method according to one of the preceding claims, characterized in that a vinyl copolymer is used, that the cyanized vinyl monomer in an amount of Contains Io to 4o percent by weight copolymerized. 5) The method according to any one of the preceding claims, characterized in that a vinyl copolymer is used with (a) up to 4o weight percent of at least one of the cyanized vinyl monomers of the formula and (b) not less than so weight percent of at least one with the cyanized vinyl monomers copolymerizable vinyl monomers from the group of aromatic vinyl monomers of the formula in which ft and R 'denote hydrogen or a lower alkyl group, and acrylic monomers of the formula ^: 009818/1839 CE ₂ = C - CO-OR ₂ , ■ ■ ir, the R "is hydrogen or a lower alkyl group and R ₂ mean a lower alkyl group, is copolymerized. 6) Method according to one of the preceding claims, characterized in that r.an is an aromatic vinyl mono ir.ere styrene is used. , 7) Method according to one of the preceding claims, characterized in that one is called Acrylnonoir.eres Kethylr.ethacrylat used. 8) Method according to one of the preceding claims, characterized by the fact that there is a higher saturated alcoholic alcohol with the formula one is used in which, η has the meaning from I ¹ J to 1-8. 0098 18/1839